Conventionally, an input image provided through image input devices such as a scanner, a video camera, and so on is firstly converted from analog form to digital through an analog-to-digital converter, then processed, analyzed, or understood by using a digital computer and/or a digital circuit.
FIG. 6 shows a typical prior art (Page 194, FIG. 1B "Special computer architectures for pattern processing, CRC Press, Inc. 1982). In the figures, the numeral 1 is an image input unit, 3 is a digital computer, 20 is a frame memory, and 99 is an image signal input terminal. The image input unit 1 carries out the analog-to-digital conversion for an input image signal applied to the input terminal 99. A frame of an image signal in digital form thus converted is stored in the frame memory 20. The computer 3 carries out the processing for the digital images stored in the frame memory 20 by using a computer program stored in the computer 3.
FIG. 7 shows another prior art (Page 7 FIG. 1.6, "Digital image processing, Addison-Wesley Publishing Company, Inc. 1977). In the figure, the numeral 21 is an image processing circuit, 22 is a connection interface. An image signal has voluminous information, as it is an information having a spatial extension, and in case of a moving picture, it has a time extension (for instance 30 frames in each second). When an image signal is processed by using a general purpose computer, it takes a long time for the processing, although the general purpose computer has the flexibility for the content of the processing which is described by software of a computer program. In order to solve this problem, a special LSI (large scale integrated circuit), and/or a special processing circuit has been developed for carrying out a fundamental operation in image processing. The image processing circuit 21 has such a special LSI and/or a special processing circuit. Some examples of the fundamental processing are a point operation, a neighboring operation by using 3.times.3 pixels (for instance, accumulation of products), and a fast Fourier transform. The fundamental processing directly handles a value of each pixel, but does not understand the content of the image. The connection interface 22 couples the computer 3 with the image processing circuit 21 so that the computer 3 controls the operation of the image processing circuit 21, and/or receives the result of the processing.
The prior art of FIGS. 6 and 7 process an input signal sequentially in the order of an input of image frames. In other words, after the processing for a frame is finished, the processing for a succeeding image frame is carried out. Even when a plurality of image processing circuits and/or calculators are used for high speed processing, image frames are spacially divided and each frame is processed by each image processing circuit, and/or a plurality of pixels are processed simultaneously. Therefore, the processing is carried out in the order of frames in the sequence of arrival. When a set of parameters for a processing is changed, the processing for each set of parameters must be carried out for each set of parameters.
Therefore, a prior image processing system is not flexible, and it is slow in processing operation.
In the case of FIG. 6 which uses a general purpose computer and describes the content of processing by computer program, it may carry out both a simple image processing and a complex image processing, it has the disadvantages that the processing speed is slow and it is almost impossible to process a moving image like a television signal on a real time basis.
In the case of FIG. 7, the high speed processing may be possible if a special circuit matches with the processing. However, as a special circuit is limited to only a fundamental processing, when a high-level processing including analysis and/or understanding of an image is intended, we must use a general purpose computer. If we use a DMA (direct memory access), or GPIB for an interface with a computer to transmit image data, it takes a long time at the interface portion.